Effect of infrared roasting on antioxidant activity, phenolic composition and Maillard reaction products of Tartary buckwheat varieties

The effect of infrared roasting (130, 150 and 170 degrees C for 10 min) on antioxidant activity, total phenolic content (TPC), total flavonoid content (TFC), Maillard reaction products (MRP) and phenolic profile in eight Tartary buckwheat (Fagopyrum tataricum) varieties were investigated. TFC (23.74-28.67 mg RE/g) remained unchanged at 130 degrees C and 150 degrees C but exhibited a sharp decline at 170 degrees C. TPC (8.90-14.72 mg GAE/g) and TAA (11.37-12.74 mu mol TE/g) decreased significantly with increase in roasting temperature. The lowest fluorescence of advanced MRP (FAST) index was observed for buckwheat roasted at 130 degrees C (230.76-338.55%) and the highest at 170 degrees C (420.30-523.72%). IC-341651 and IC-107994 had high antioxidant properties and SMLBW-4 exhibited lowest browning index (BI), free fluorescent intermediate compounds (FIC) and FAST index, indicating the least MRP formation. Gallic acid and quercetin were detected in only bound and free-form, respectively. Rutin was the most thermostable polyphenol detected in all buckwheat varieties.